Actually, you’d get a lot of gamma rays pointing down, where down is defined as “towards the Earth.” They would be a whole bunch of low-energy albedo and limb gammas that swamp the instrument. It’s like when you are out looking at stars and someone turns on the porch light. Ow! Plus, to a gamma-ray astronomer, they are boring.

I think GLAST would be better off pointing to the curtains, to try to resolve the inverse-Compton coming from Tigger. He moves fast enough, I’d say.